Why FEI (Fan Energy Index) is the Future of Fan Efficiency in Commercial Buildings.
When it comes to energy efficiency, most building owners and engineers want real answers — not outdated metrics. For years, the FEG (Fan Energy Grade) rating was used to indicate fan efficiency, but let’s be honest: it never truly reflected how fans perform in the real world.
Enter FEI— the Fan Energy Index — a much smarter, more practical way to evaluate fan energy use based on how fans are actually applied in commercial buildings.
At ACI Mechanical, we work with hospitals, schools, universities, and countless other commercial facilities where HVAC systems aren’t just a comfort feature — they’re critical infrastructure. That’s why we advocate for using FEI to select fans. It gives engineers and owners a clear picture of how much energy a fan will use under actual field conditions, not just in a lab.
Here’s why FEI matters:
It reflects real operating points — not full throttle only ones.
It encourages better fan selection and system design.
It helps owners visualize long-term energy and cost savings.
It aligns with how modern building systems are engineered and maintained.
FEI selections are the law now and it’s how we help our clients deliver sustainable, high-performing buildings every day.
Want to learn more about how proper fan selection can cut energy costs in your facility? Let’s talk.
